Fluorosensors based on Eu(III) ternary complex of DO3A ligand
Filip Smrčka,a)
Přemysl Lubal,a,b)
a) Department of Chemistry, Faculty of Science, Masaryk University, Kotlářská 2,
CZ–611 37 Brno, Czech Republic
b) Central European Institute of Technology (CEITEC), Masaryk University, Kamenice 5,
CZ–625 00 Brno, Czech Republic
Specific spectroscopic, electrochemical and magnetic properties of Ln(III) ions make
them perfect candidates for use in many chemical, biological and environmental systems.
Ln(III) complexes with macrocyclic ligands (mainly DOTA derivatives) are commonly
utilized in medicinal chemistry as radiopharmaceuticals (90
Y, 153
Sm, 166
Ho, 177
Lu) [1,2] and
contrast agents for MRI (Gd) [3].
The 1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid (H3DO3A) as heptadentate
ligand forms a stable complex with europium(III)/terbium(III) aqua ion. The ternary
[Ln(DO3A)L] complex exhibits a high luminescence due to antenna effect leading to
sensitization of Eu(III)/Tb(III) luminescence by a fluorophore (e.g. picolinic or isoquinolic
acid) via efficient energy transfer from ligand to Ln(III) ion. The utilization of those ternary
Eu(III) and Tb(III) complexes as selective dual luminescence/electrochemical sensors for
determination of carbonate/oxalate using substitution reaction was reported [4, 5]. This was
also employed for indirect determination of carbonate formed in the course of urea hydrolysis
catalyzed by the urease enzyme (see Scheme).
The inhibition effect of some metal ions (e.g. Ag+
, Pb2+
, Zn2+
, Cd2+
) on enzymatic
reaction can be employed for their analytical determination [6]. The proposed analytical
procedure is fast, selective and sensitive with metrological parameters comparable for other
urea biosensors. As it is known to authors, this new biosensor is the first example of biosensor
using the bicarbonate detection as the product of urea hydrolytic reaction catalyzed by urease.
Scheme: The cascade reaction of the ternary [Eu(DO3A)(Pic)]- complex employed for enzymatic
determination of urea.
Analogously, this general approach was verified on example of enzymatic reaction
when the course of ethanol transformation catalyzed by alcohol-dehydrogenase (ADH) was
followed by luminescence spectroscopy which can be utilized for selective and sensitive
determination of ethanol concentration and/or ADH enzyme activity.
The oxidative reaction of ethanol to acetaldehyde coupled with the reduction of NAD+
to NADH is catalyzed by ADH enzyme:
CH3CH2OH + NAD+
→ CH3CHO + NADH + H+
and it leads to change of NAD+
/NADH ratio which helps to follow metabolic effects of
ethanol in human body.
References:
[1] Wadas TJ, Wong EH, Weisman GR, Anderson CJ (2010) Chem Rev 110:2858
[2] Försterová M, Jandurová Z, Marques F, Gano L, Lubal P, Vaněk J, Hermann P, Santos I (2008) J
Inorg Biochem 102:1531
[3] Hermann P, Kotek J, Kubíček V, Lukeš I (2008) Dalton Trans 23:3027.
[4] Vaněk J., Lubal P., Hermann P., Anzenbacher P., Jr. (2013) J. Fluorescence 23:57.
[5] Vaněk J., Smrčka F., Lubal P., Třísková I., Trnková L. (2016) Monatsh. Chem. 147:925.
[6] Smrčka F., Lubal P., Šídlo M. (2017) Monatsh. Chem. 148:1945.